Electrical connector contact and insulator retention system



March 9, 1965 J KELLY 3,172,721

ELECTRICAL CONNECTOR CONTACT AND INSULATOR RETENTION SYSTEM Filed June 20, 1962 3 Sheets-Sheet 3 FI/GO INVENTOR. I (7055 1, R KELLY 88 4 0 flrroxavsYs.

March 9, 1965 Filed June 20, 1962 J. F. KELLY ELECTRICAL CONNECTOR CONTACT AND INSULATOR RETENTION SYSTEM 3 Sheets-Sheet 1 mvsmoa ZOSEPH F! March 9, 1965 ELECTRICAL CONNECTOR CONTACT AND INSULATOR RETENTION SYSTEM Filed June 20, 1962 J. F. KELLY 3,172,721

3 Sheets-Sheet 2 T 36 C V 42 ,--32

20 v INVENTOR.

tiosspfl 1 KELLY firraeus Y5.

United States Patent ()fiice 3,l72,72l Patented Mar. 9, 1965 3,172,721 ELECTRICAL CGNNECTQR CONTACT AND HNSULATOR RETENTEON SYSTEM Joseph F. Kelly, Scottsdale, Ariz., assignor, by mesne assignments, to international Telephone and Telegraph Corporation, New York, N.Y., a corporation of Maryland Filed lune 20, 1962, Ser. No. 203,887 23 Claims. (Cl. 33-217) The present invention relates to electrical connectors, and it relates particularly to novel retention structure for releasably retaining the contact terminals in the connector insulators or for releasably retaining the insulators in respective outer shells of the connector members, wherein the retention structure permits the contact terminals or insulators to be snapped into their operative positions, in which positions the retention structure afiords an effective seal against the passage of fluids such as moisture or potting compounds into the contacting area.

Electrical connector designs are known wherein the contact terminals may be mounted in the insulation body by pushing the terminals into respective bores in the insulation body, and wherein snap-in retention means is prov ded for locking each terminal in its operative position in its respective bore. It is also known to provide similar snap-in mounting of the insulation bodies in respective outer shells of the connector. Such snap-in retention means usually takes the form of a split ring or clip of spring metal either mounted on the member to be snapped into position or mounted within the bore or opening within which it is to be mounted. However, such conventional spring metal locking devices have the disadvantage that liquids can readily pass by them, so that moisture can seep past the contact members or insulation bodies from the rear of the insulation bodies forwardly into the contacting area. Also, with such conventional snap-in retention means it is diflicult or impossible to employ a potting compound, which is applied in the form of a viscous liq id that is poured about the contact terminals and wires connected thereto in the region of the rear face of the insulation body, as the potting compound will flow forwardly between the contact terminals and their respective bores or between the insulators and their respective outer shells and thence past the retention means into the contacting area, injuring both the mechanical and electrical mating characteristics of the contact terminals.

Another problem in connection with conventional metal rings or clips employed for the snap-in retention of either the contacts or the insulators is that they are likely to abrade or otherwise damage the opposing shoulder of the insulation body where the retention force is applied. Such retention structures also have a tendency to damage the insulation body under conditions of vibration. Further, some spring metal retention clips employed for retaining contacts within respective insulator bores have rather delicate spring retention fingers which are easily bent or otherwise damage In View of these and other problems in connection with conventional snap-in retention structures for electrical contacts or insulators, it is an object of the present invention to provide a novel retention bushing composed of a resilient plastic material, the bushing having a head portion seated against axial movement in a groove either on the member to be retained or in the bore or opening within which the member is retained, and having a tapered skirt portion which deflects toward a lesser taper during insertion of the member and then snaps back to an increased taper behind a retention shoulder in the bore or opening or on the member as the case may be, and

in this position the entire tapered part of the bushing is in shear to provide high retention forces and is Under radial compression in an interference fit so as to afford a seal between the member and the wall of the bore or opening.

Another object of the present invention is to provide a novel snap-in retention bushing for contact or insulator retention in an electrical connector, wherein the head portion of the bushing has an iternal flange which seats in a groove in the member to be snapped into position and the skirt portion of the bushing flares rearwardly and radially outwardly, the preferred angle of flare being greater than 15 degrees relative to the connector axis, or greater than a 30 degree included angle in the uncom-i pressed condition of the bushing to obtain the desired interference fit seal between the member and the wall of the bore or opening into which the member is snapped.

A further object of the invention is to provide a resilient tapered or flared plastic bushing of the character described for the snap-in retention of contacts or insulators in an electrical connector, wherein the bushing is preferably composed of a tough fiuoroethylene material having a high degree of elastic memory such as Kel-F, whereby the tapered or flared portion of the bushing will dei ect toward a more axially oriented position during insertion of the member into the bore or opening, and will then snap to an increased taper in a tightly sealed resilient interference fit in the operative position of the member.

Another object is to provide a contact retention system of the character described which utilizes a minimum of peripheral space about the individual contacts and insulators, and wherein the retention structure is composed of dielectric material, whereby maximum contact density may be provided with minimum overall connector dimensions, and whereby electrical creepage is minimized.

A still further object of the invention is to provide a retention system of the character described which is simple in construction and economical to manufacture, yet which is positive acting in both its retention and its sealing functions.

A further object of the present invention is to provide a retention system of the character described wherein the novel resilient plastic bushing provides both a low pressure seal against the passage of moisture from the rear of the insulator forwardly to the contacting area and a complete seal against the passage of potting materials from the rear of the insulator into the contacting area.

Another object of the invention is to provide a retention system of the character described wherein the contact members can be readily removed and replaced without damaging the insulator either by employing a contact extraction tool of the type which constricts the retention bushing so that it clears the opposing shoulder in the insulator bore, or by impact removal, and wherein the resilient retention bushings are readily replaceable in the event they are damaged.

It is an additional object of the invention to provide a retention system of the character described for an electrical connector wherein the contact retention means, comprising a resilient plastic bushing, will not damage the insulation body upon vibration or upon shifting of the contact members due to manipulation of the connector, and wherein the resiliency and configuration of the bushings are such as to provide restricted radial float of the contact members to compensate for possible misalignment between the mating contact components.

These and other objects and advantages of the invention will become more apparent from a consideration of the description which follows taken in conjunction with the drawings.

In the drawings:

FIG. 1 is a fragmentary vertical section, with portions in elevation, illustrating a pair of insulation bodies having mateable contact terminals supported therein by the retention system of the present invention.

FIGS. 2, 3 and 4 are enlarged vertical sections, partly in elevation, illustrating three difierent positions of the pin contact terminal member of FIG. 1 with respect to its insulation body as the terminal is being snapped into its operative position in the insulation body.

FIG. 5 is a greatly enlarged perspective view illustrating one of the resilient plastic retention bushings employed in the present invention to retain the contact terminals in the insulators.

FIG. 6 is a side elevation view, partly in vertical section, illustrating the use of a replacement arbor for replacing the resilient plastic bushing on one of the contact terminals.

FIGS. 7 and 8 are enlarged vertical sections, partly in elevation, illustrating the use of a front entry extraction tool for extracting the contact terminal from its respective insulation body.

FIG. 9 is a vertical section, partly in elevation, illustrating a socket contact terminal retained by the present system in a two-piece insulation body having a constricted bore portion forward of the socket terminal, and showing the use of an impact contact extraction tool in connection therewith.

FIG. 10 is a vertical section, partly in elevation, illustrating the pin contact terminal and insulation body of FIGS. 1 and 4 with a potting material aplied to the rear of the insulation body, showing the manner in which the resilient plastic retention bushing of the present invention affords a seal against entry of the potting material into the contacting region.

FIG. 11 is a vertical section, partly in elevation, illustrating the manner in which the connector insulation bodies may be retained in the respective connector shells by the present retention system.

FIG. 12 is a greatly enlarged view of a portion of FIG. 11.

FIG. 13 is a greatly enlarged fragmentary sectional view of another portion of FIG. 11.

FIG. 14 is an enlarged perspective view illustrating one of the resilient plasticretention bushings employed in the present invention to retain the insulators in the outer connector shells.

Referring at first to FIG. 1 of the drawings, an elecfragmentary sectional trical connector it? has been illustrated in this figure, and

includes a pair of connector members comprising respective insulation bodies 12 and 14. In some types of electrical connectors, such as the one shown in FIG. 11, the insulation bodies 12 and M will be supported in respective outer connector shells, and in others the insulation bodies themselves will form the outer structural members for the mating connector parts.

Referring at first to the insulation body 12, a bore 15 extends therethrough from the rearward face 16 to the forward face 17 of body 12. Bore 15 includes a general- 1y cylindrical contact mounting portion 18, a forward counterbore portion 20 and a rearward counterbore portion 24. The contact mounting portion 18 and forward counterbore portion 2t) intersect at a forwardly facing shoulder 22, while the contact mounting portion 18 and the rearward counterbore portion 24 intersect at a rearwardly facing shoulder 26.

Mounted in the bore 15 in insulation body 12 is a pin contact member 28. The pin contact member 28 has a cylindrical mounting portion 36 which is disposed within the contact mounting portion 18 of the bore with a slightly loose fit to permit some lateral shifting of the pin contact member for alignment thereof with a mating socket contact member. Immediately to the rear of the cylindrical mounting portion 343 of contact member 2% is an annular collar 32 that is adapted to abut against the rearwardly facing shoulder 26 in the bore to limit forward movement of the contact member 28 when it is inserted into the bore from the rear. Rearwardly of the collar 32 is a crimp or solder sleeve 34 within which the bared end of a wire 36 is electrically and mechanically connected by crimping or soldering.

Oifset forwardly of the cylindrical mounting portion 30 of contact member 28 is an annular flange 38, and pin contacting portion 4d of the contact member 28 projects forwardly from the flange 38. Intermediate the cylindrical mounting portion 39 and the flange 38 is an annular recess 42, with an annular groove 44 disposed therein adjacent to flange 33, so that the annular recess 42 is of stepped configuration.

Contact retention bushing 4b is mounted in the annular recess 42, the bushing 46 being longitudinally split and composed of a flexible plastic dielectric material. Although the present invention is not necessarily limited to the use of any particular flexible plastic material, examples of some materials which have been found suitable for the bushing t6 are Nylon; :1 iluoroethylene material, such as Teilon or Kel-F; an acetal material, such as Delrin";

or a polycarbonate material, such as LeXan. The presently preferred material is Kel-F" because of its toughness and elastic memory.

The contact retention bushing 46 includes a generally cylindrical head portion $3, and a rearwardly extending, flared skirt portion 59 of frusto-conical shape. The head portion 48 has an annular internal projection 52 which projects radially inwardly so as to seat within the groove 44. in the relaxed or unstressed condition, the longitudinal slit in the bushing 26 is closed. The bushing 46 is expanded so that it can be slipped rearwardly over the annular flange as, and then it is allowed to constrict back to a slightly expanded position within the annular recess 42, with the internal projection 52 of bushing 46 seated within annular groove The slit in bushing 46 will not completely close at this time since the internal diameter of the bushing projection 52 in the closed condition of the bushing is slightly less than the diameter of the bottom of groove 44. However, when the contact supporting the bushing 4-6 is operatively positioned within its insulator bore, the bushing Will be placed in radial compression, which causes the slit to close and the bushing flange 52 to be disposed in a sealed, interference relationship with the contact member 23 in the region of groove 4:4.

The outermost edge of the frusto-conical skirt portion 54) of bushing 46 has a normal relaxed diameter (with the slit closed) that is larger than the forward counterbore portion 2t of the bore 15 so that when the contact member 28 is operatively positioned in the bore 15 and the bushing 46 is in counterbore 20, the skirt portion of the bushing will be compressed radially inwardly by the wall of counterbore 20 to not only completely close the longitudinal slit in the bushing but to also provide a sub stantial interference between the outer edge of the skirt portion 5% of the bushing and the wall of counterbore 20 such that a sealed relationship is established.

In this manner, the contact retention bushing 46 will provide a substantially liquid-tight seal between the contact member 23 and the insulation body 12, thus protecting the forward pin contacting portion 46 of the contact member 28 from moisture which might otherwise be admitted through the bore from the rear 0 fthe insulation body. The bushing 46 affords an excellent seal against relatively viscous liquids, such as potting compounds, so that potting compounds can be freely applied in the usual manner by pouring them against the rearward face 16 of the insulation body without danger of the potting compound flowing into the contact mating region.

The angle of the flare of the skirt portion 56 of bushing 46 is an important factor in establishing a sufficiently tight interference fit of the bushing 46 between the contact member and the wall of the counterbore 26 to provide the desired effective seal and to provide the desired contact retention forces. If the flare angle is too small, then radial rigidity of the skirt portion 59 will not be sufficient to effect a good seal or good retention. It has been found in practice that the flare angle is preferably greater than degrees relative to the axis of the contact (i.e., a total included flare angle greater than degrees) when the bushing 46 is in its free or unstressed condition, in order to provide the desired sealing and retention characteristics. A presently preferred flare angle in the free condition of bushing 46 is about 18 degrees (a total included angle of about 36 degrees). It is preferred not to have the flare angle greater than about 25 degrees (a total included angle of about degrees), as too great a flare angle would make it difficult to insert the contact in the insulator bore and would be likely to cause the skirt portion to double over during insertion of the contact.

FIGS. 2, 3 and 4 illustrate the insertion of pin contact member 28 into the bore 15 of insulation body 12 from the rear. In FIG. 2 the forward portion of the contact member 28 has been inserted into the bore 15, but the rearwardly flaring skirt portion 59 of the contact retention bushing 46 has not been pushed forwardly into the constricted contact mounting portion 18 of the bore. In FIG. 3, the contact member 28 has been advanced so that the entire bushing 46 is disposed within the constricted contact mounting portion 18 of the bore, the skirt portion 59 of the bushing 46 being constricted to a position in which it is to a large extent disposed within the annular recess 42. The rearwardly flaring incline of the skirt portion 59, coupled with the cantilever mounting of the bushing 46 as best seen in FlG. 2 created by engagement of the internal projection 52 of the bushing within the groove 44, make it relatively easy to push the contact member 28 forwardly from the position shown in FIG. 2 to the position of FIG. 3.

The contact member 28 may be pushed into the insulator bore either by directly gripping the contact member between the fingers, or by employing a suitable contact insertion tool such as tool 54 shown in FIG. 3. In the case of very small contact terminals, in connection with which the present invention has particularly utility, it is desirable to employ a contact insertion tool such as the tool 54. The tool 54 is trough-shaped, having a forward lip that engages the annular collar 32 on the contact for applying the forwardly directed insertion force required to push the contact terminal into the bore of the insulator.

When the contact member 28 reaches its forwardmost position in the bore 15 as determined by engagement of the annular collar 32 against the rearwardly facing bore shoulder 26, the rearward edge of the bushing skirt 50 will clear the forwardly facing bore shoulder 24 and the skirt 5% will then snap radially outwardly to its position as shown in FIG. 4 so as to lock the contact member 28 in position within the bore, with the outer periphery of the skirt 5t engaged in sealing relationship against the wall of counterbore 243. In this position of the contact member, the contact retention bushing 46 provides positive 360 shouldered retention for the contact member, with the entire frusto-conical portion 5%) of the bushing being in shear upon the application of a rearwardly directed force to the contact member. Thus, the bushing 46 provides high retention force against rearward removal of the contact terminal through the bore.

Referring again to FIG. 1, the insulation body 14 is considerably thicker than the insulation body 12 in order to accommodate a fully recessed socket contact member. The insulation body 14- has a bore 55 extending therethrough from the rearward face 56 to the forward face 57, the bore 55 including a contact mounting portion 58 of generally cylindrical configuration, with an enlarged forward counterbore portion 60 and an enlarged rearward counterbore portion 62.

A socket contact member 64 is mounted in bore 55 contact member 64 having a cylindrical mounting portion 65 disposed within the mounting portion 58 of bore 55, preferably with a slight amount of tolerance provided to permit contact shifting for alignment. The socket contact member 64 has an annular collar 66 immediately to the rear of the cylindrical mounting portion 65 of the contact member to limit forward movement of the contact member in the bore. Forward of the mounting portion 65 the contact member 64 is provided with an annular flange 67, and a socket contacting portion 68 extends forwardly from the flange 67 and is adapted to mate with the pin contacting portion 49 of the contact member 28. The entire forward socket contacting portion 68 is recessed within the elongated forward counterbore portion 6% of the bore 55 in the form of electrical connector shown in FIG. 1.

An annular recess 69 is provided between the cylinrical mounting portion s5 and the annular flange 67 of the contact member 64, and one of the contact retention bushings 46 is mounted in the annular recess 69. The mounting of the bushing 46 on the socket contact member 64 is identical to the mounting of bushing 46 on the pin contact member 28, and the contact member 64 is inserted and retained in the bore 55 in exactly the same manner as the contact member 28 is inserted and retained in the bore 15.

FIG. 6 of the drawings illustrates a replacement magazine in the form of an arbor '70 which may be employed for conveniently mountin a contact retention bushing 46 on one of the contact members. In FIG. 6 the arbor 70 is shown operatively associated with the pin contact member 23, although it is designed to also be employed in connection with the socket contact member 64.

The arbor 7ft includes an elongated rod portion 72 upon which a multiplicity of the contact retention bushings as may be slidably engaged. For example, as many as 50 or more bushings 46 may be disposed on the rod portion 72. A retention pin 74 is removably engaged through an end of the rod portion 72 so as to hold the bushings 45 in position on the rod portion 72, but to permit reloading of the device. At the other end of the rod portion 72 the replacement arbor 7t) flares outwardly in a ramp portion 76 to an enlarged tubular guide portion 78 having an internal diameter sufiicient to accommodate the pin contacting portion t-tl of contact member 28 or the socket contacting portion 63 of contact member 54. In operation, the contact member 28 has its forward contacting portion inserted into the tubular guide portion 7 S of arbor 7d until the exposed edge of the guide portion '73 abuts against the annular flange 38 of the contact member 23, and the contact retention bushing 46 nearest the flared ramp portion 76 is grasped with the fingers and is slidahly moved in an axial direction up the ramp portion 7a, which expands the bushing 46, and thence along the tubular guide portion '78 and over the flange 38 of the contact and into its operative position in the annular recess 42 of the contact, at which time the bushing will resiliently contract so as to be operatively disposed in the recess 42. Disposal of one of the bushings 46 on a socket contact member is accomplished in the same manner.

The arbor 7t) can be employed in the initial mounting of the contact retention bushing 46 on the contact member, or can be employed to replace a damaged bushing which has been removed from the contact member.

FIGS. 7 and 8 illustrate the removal of contact member 28 from insulation body 12 with the aid of a contact extraction tool 843. The tool 80 has an elongated body 82 with a thin-Walled forward sleeve portion 84. This forward sleeve portion 84 is pushed into the forward counterbore 20 so as to surround the forward part of the terminal member and the bushing 46, and the sleeve portion $4 collapses the skirt portion 54! of bushing 46 within the annular recess 42 so that the rearward edge of the skirt portion 54 clears the forwardly facing bore shoulder 24. The tool body 82 has a bore 86 extending thcrethrough in axial alignment with the thin-Walled forward sleeve portion 84 and communicating with the inside of sleeve portion 84. The pin contacting portion 46 of the contact member 23 is received in this bore 86, and a center shaft 88 is slidable within the bore 86. When the body of the tool is moved forwardly so that the sleeve 84 is fully inserted into the counterbore 29 of the insulation body and the bushing skirt 56 is collapsed as shown in FIG. 7, then the center shaft 88 is pushed vagainst the pin contacting portion 443 of the contact member 28 as shown in FIG. 8 so as to move the contact member 23 rearwardly through the insulation body bore. Alternatively, with the skirt collapsed, the contact member 23 can be grasped at its rear end and pulled rearwardly through the insulation body bore.

One of the advantages of the present contact retention system is that it can be employed in a one-piece insulator, thus eliminating the moisture trap normally present at the interface between the two insulation blocks of a twopiece or split insulator which is required with most contact retention systems. By thus eliminating the moisture trap of a two-piece insulator, electrical losses between the contacts are reduced and closer contact spacing is permitted. Accordingly, the present invention is ideal for very small connectors having small contact members, such as the miniature and sub-miniature types of connectors.

However, in some cases it may be desirable to provide a multiple block insulator construction, and even in that case the contact retention bushing of the present invention wiil minimize moisture entrance into the split insulator area and particularly into the mating area of the contacts. An example of a two-piece or split insulator is the insulator 90 illustrated in FIG. 9 of the drawings, which comprises a front insulator member 92 and a rear insulator member 94. The rear insulator member 94 has a bore 96 extending therethrough, with an enlarged rearward counterbore 98. Axially aligned with the bore 96 is a bore 100 in the front insulator member 92, the bore 160 having a larger diameter than the bore 96, and having a constriction 102 proximate its forward end. By providing the bore 100 with a larger diameter than the bore 96, an annular portion of the forward face 104 of the rear insulator member 94 will present a forwardly facing shoulder in the two-piece insulator 96 against which one of the contact retention bushings 46 will lodge in the manner hereinabove described in detail.

The constricted portion 102 of bore is provided with a flared entrance 106 at the forward face of front insulator member 92 for guiding a pin contact member into the bore 100.

A socket contact member 108 is shown disposed in the axially aligned bores $6 and 10b, and includes a generally cylindrical mounting portion 110 lodged in the bore 96, with an annular collar 111 disposed rearwardly of the cylindrical portion 110 for limiting the forward movement of contact member 108. An annular flange 112 is disposed forwardly of the cylindrical mounting portion 110 and within the bore 160, with a forward socket contacting portion 11 of the contact member 108 extending forwardly from the flange 112 and disposed within the bore 190. One of the contact retention bushings 46 is operatively positioned in an annular recess 116 between the cylindrical mounting portion 110 and the flange 112. The two-piece insulator d0 illustrated in FIG. 9 is referred to as a closed-entry insulator due to the constricted forward portion 102 of bore 160 behind which the socket contact member is disposed. With the unique contact retention bushing 46 of the present invention, the contact member 108 can be removed rearwardly from the insulator 90 without separating the two portions of the insulator merely by employing an impact tool 118 having a pin portion 12%? which is inserted through the constricted portion 102 of bore 104? and into the contacting portion 114 of the socket contact member 108. A rearwardly directed impact provided by the tool 118 will force the contact member 108 rearwardly through the bore 96. Although this will probably damage the bushing 46, the bushing can be readily replaced in the manner hereinabove described.

FIG. 10 illustrates the manner in which the contact retention bushing 46 seals off the contacting area when a potting material is employed for permanently sealing the rear of the connector member. It is conventional practice with some connectors to pour a viscous potting material, which will later substantially harden, against the rear face of an insulation body within which contact members are mounted so as to completely surround and waterproof the rear ends of the contact members and the connections of the wire conductors to the contact members. However, this cannot be done with contacts employing conventional spring metal snap-in retention rings or clips because the potting material flows forwardly past the retention means and fouls the contact terminals. However, referring to FIG. 10, which illustrates the application of a potting material 122 to the insulation body 12 having contact member 28 mounted therein, it will be seen that when the viscous potting material 122 is poured so as to fill the region behind the rear face 16 of insulator 12, the potting material may seep forwardly through the rear counterbore 22 and the constricted contact mounting portion 18 of the bore 15, but will be trapped by the frusto-conical skirt portion 50 of bushing 46 so that it cannot flow into the forward counterbore 20 and become deposited on the forward contacting portion of the contact member 23. Any pressure of the potting material which reaches the inside surface of skirt portion will actually tend to fiare the skirt 50 radially outwardly into a more tightly sealed relationship with the wall of forward counterbore 29.

Although the present invention has been illustrated in connection with pin and socket contact members of generally conventional construction, it is to be understood that it is equally applicable to other types of contact members, as for example hermaphrodite contact members or others. 1

FIGS. 11-14 illustrate the manner in which the present retention system may be applied to the releasable snap-in mounting of electrical connector insulation bodies in the outer shells of the connector members.

The electrical connector 124 shown in FIG. 11 includes a receptacle member 126 and a plug connector member 123 which is receivable in the receptacle member 126.

The receptacle connector member 126 includes an open-ended tubular shell 130 having an outer flange 131 for mounting purposes, and having a forward portion 132 which is adapted to receive the forward part of the plug connector member 128. The passage extending through i the receptacle shell 130 is of stepped configuration, having a relatively small diameter rearward portion 133, a relatively large diameter forward portion 134, and a central portion 135 of intermediate diameter.

The central portion 135 of the bore or passage through receptacle shell 130 has an annular recess 136 of stepped configuration formed therein, an annular groove 138 being provided in the forward part of the recess 136. Insulator retention bushing 140 is mounted in the annular recess 136, the bushing 140 including a generally cylindrical head portion 142 and an inclined skirt portion 144 which extends rcarwardly and radially inwardly from the head portion 142. An external annular projection 146 is formed on the head portion 142 and seats within the annular groove portion 138 of recess 136. The bushing 140 may be of closed annular configuration, or it may be longitudinally split in the same manner as the contact terminal retention bushing 46 shown in FIGS. 1-10.

The insulator retention bushing 140 is composed of the same type of material as bushing 46, and the skirt portion 144 of bushing 140 has the same preferred angle of incline and range of angles with respect to the axis of the connector as the contact terminal retention bushing 46. The bushing 140 difiers from bushing 46 in two principal respects: (1) It is a great deal larger circtunferentially, encircling the entire insulation body instead of merely a single contact terminal member; and (2) in order for the skirt portion 144 to extend rearwardly from the head portion 142 so as to entrap liquids tending to move forwardly through the receptacle connector member, since the bushing is mounted in the wall of the receptacle shell, the skirt portion 144 inclines rearwardly and radially inwardly instead of inclining rearwardly and radially outwardly as with the bushing 46.

The receptacle shell 130 includes a forwardly facing internal shoulder 148 formed between the bore portions 133 and 135, and also includes an externally threaded rear portion 150 which is adapted to receive either a potting compound or a conventional internal sealing grommet, as well as an internally threaded end bell, these parts being conventional and therefore not being shown in the drawing.

The insulation body 152 to be mounted in receptacle shell 136 and which supports one or more contact terminals therein is of stepped peripheral configuration, having a relatively large diameter rearward peripheral portion 154- and a relatively small diameter forward peripheral portion 156, these portions meeting at a forwardly facing shoulder 158.

The insulation body 152 is inserted into the receptacle shell 139 from the forward end thereof, and is pushed rein-wardly until the rear surface of insulation body 152 abuts against the forwardly facing shoulder 148 in the shell, the skirt portion 1 34 of bushing 14% being deflected radially outwardly as the rearward peripheral portion 154 of the insulator passes thereby, and snapping back radially inwardly into abutment with the forwardly facing insulator shoulder 158 and into sealing relationship with the forward peripheral portion 155 of the insulator.

The insulator 152. can be removed merely by inserting a simple thin-walled tube-like tool into the forward end of the receptacle shell 13%) and between the forward peripheral portion 156 of the insulator and the central portion 135 of the shell passage so as to deflect the skirt portion 144 of bushing 14% radially outwardly out of engagement with the forwardly facing insulator shoulder 158, permitting the insulator to be pushed forwardly out of the shell.

In order to illustrate the fact that the resilient plastic retention bushing can be either mounted in the shell or on the insula ion body, the retention bushing 14d associated with the receptacle member 126 has been shown mounted within the shell 13%), while the retention bushing associated with the plug connector member 128 has been illustrated to be mounted about the periphery of the respective insulation body. In either case, the bushing can be either continuous or split, the relatively large circumference of the bushing permitting sufiicient compression or expansion of the bushing so that it can be seated in its groove even though the bushing may not be split.

Referring now specifically to the consn'uction of the plug member 128, it includes an oper -ended tubular shell 16% having an external mounting flange 162, and having a forward portion 154 that is receivable within the forward portion 132 of the receptacle shell 131' The for ward portion 164- of the plug shell has an external key 1655 thereon which is received within an axial slot 3-58 within the forward portion 132 of receptacle shell 13! for polarizing purposes.

The bore or passage extending through the plug shell 16% includes a constricted portion 1%, a slightly en larged forward counterbore portion 172, and an enlarged rearward counterbore portion 173. The bore portions 171 and 172 meet at a forwardly facing shoulder 174, while the bore portions Fit) and 173 meet at a rearwardly facing shoulder 176. The plug shell 160 also includes an externally threaded rear portion 178 for receiving a potting compound or a sealing grommet, and upon which an end 'bell is threadedly engaged.

The plug insulation body 180 includes a relatively large diameter rear peripheral portion 182 and a relatively small diameter forward peripheral portion 184, the por tions 182 and 184 of the periphery meeting at a forwardly facing shoulder 186. The forward peripheral portion 184 of the insulation body has an annular recess 188 therein of stepped configuration, the forward portion of which includes an annular groove 1%.

The insulator retention bushing 192 is constructed of a similar material and has a similar cross-sectional shape to the contact terminal retention bushing 46 heretofore described detail, except for size, and with the further exception that the longitudinal split in the bushing 192 is optional. Thus, the retention bushing 192 includes a generally cylindrical head portion 194, a re-arwardly and outwardly flaring frusto-conical skirt portion 196, and an internal annular projection 1%, the projection 198 seating within the annular groove 1%.

The plug insulation body 18% is inserted into the plug shell lot) from the rear, the skirt portion 196 of bushing 192 deflecting radially inwardly so as to pass forwardly through the constricted portion 179 of the bore in the shell, and then snapping radially outwardly so as to be in abutting relationship with the forwardly facing shoulder 174 in the shell and so as to be in sealing relationship with the forward counterbo-re portion 172 of the shell bore. Rearward removal of the insulation body 180 is permitted by inserting a tubular removal tool in the annular space between the forward counterbore 172 of the plug shell and the forward peripheral portion of the insulator 180 so as to constrict the skirt portion 196 of bushing 1% out of engagement with the shell shoulder 174, thus permitting the insulator to be pushed rearwardly out of the shell.

Although the receptacle and plug shells and insulators, and the retention bushings associated therewith, have been shown and described as being of generally circular, annular form, it is to be understood that these may have other cross-sectional shapes, as for example square or rectangular, and that the peripheral configurations thereof are not limited to circular forms.

The present retention system as applied to the removable retention of insulation bodies in electrical connector shells requires a minimum of peripheral area, thus allowing more available space for contact layout within a given size connector, and permits the insulators to be inserted into and removed from the shells quickly and easily. Installation of the insulators is by a simple snapin operation, not requiring fitting of the conventional metal retaining rings normally used. Retention is positive, and an effective seal is provided against the passage of moisture or potting compounds forwardly past the insulators into the mating area of the contact terminals. By providing the retention bushings for the insulator inserts of dielectric material the electrical creepage distance between the retention member and the nearest contacts is minimized, so that additional space is not required to keep down creepage as is required with metal retaining ring retention structures.

While the instant invention has been shown and described herein in what are conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.

I claim:

1. An electrical connector unit comprising a support member having front and rear ends and having a passage extending therethrough between said ends, a supported member insertable into said passage from one end so as to be supported therein with a portion of the surface of the passage in overlapping relationship with a peripheral surface portion of said supported member, stop means on said members engageable to limit the insertion of said supported member in the passage, and snap-in retention means engageable between said members for retaining and moisture sealing said supported member in said passage of the support member, said retention means comprising a groove in one of said surface portions, a generally axially facing shoulder on the other of said surface portions, and a retention bushing composed of a tough, resilient plastic material having a generally cylindrical head portion at one end thereof and a generally annular inclined skirt portion extending from said head portion to the other end thereof and terminating in a generally annular face, said head portion having a flange thereon which is seated within said groove so as to restrain the bushing against relative axial movement, and said skirt portion inclining toward said other surface portion with the face of the skirt in generally annular abutting relationship with said shoulder and engaged against said other surface portion when said supported member is in its fully inserted position in said support member, said skirt portion having a wall thickness less than the radial dimension between the contiguous surface of the supported member and the radially adjacent wall of the passage and said bushing having a resilient, radially compressed substantially 360 interference fit between said surface portions and completely encompassing said supported member in said fully inserted position providing a moisture seal between said members.

2. An electrical connector unit as defined in claim 1 wherein said skirt portion of the bushing inclines at an angle of greater than 15 degrees relative to the axis of the bushing when the bushing is in its free, uncompressed condition.

3. An electrical connector unit as defined in claim 1 wherein said skirt portion of the bushing inclines at an angle of greater than 15 degrees and not greater than 25 degrees relative to the axis of the bushing when the bushing is in its free, uncompressed condition.

4. An electrical connector unit as defined in claim 1 wherein said skirt portion of the bushing inclines at an angle of about 18 degrees relative to the axis of the bushing when the bushing is in its free, uncompressed condition.

5. An electrical connector unit as defined in claim 2 wherein said bushing is composed of a fluoroethylene plastic material.

6. An electrical connector unit as defined in claim 2 wherein said skirt portion of the bushing extends in a rearward, inclined direction from said head portion of the bushing,

7. An electrical connector unit as defined in claim 6 wherein said groove is in said peripheral surface portion of the supported member and said shoulder is on said passage surface portion of the support member, said skirt portion of the bushing flaring rearwardly and radially outwardly from said head portion of the bushing.

8. An electrical connector unit as defined in claim 6 wherein said groove is in said passage surface portion of the support member and said shoulder is on said peripheral surface portion of the supported member, said skirt portion of the bushing inclining rearwardly and radially inwardly from said head portion of the bushing.

9. An electrical connector unit comprising an insulation body having front and rear ends and having a passage extending therethrough between said ends, an elongated contact terminal member insertable into said passage from the rear so as to be supported therein with a portion of the surface of the bore in overlapping relationship with a peripheral surface portion of the contact terminal, stop means on the insulation body and contact terminal member engageable to limit the insertion of the contact terminal member in the passage, and snap-in retention means engageable between said insulation body and contact terminal member for retaining and moisture sealing said contact terminal member in the passage, said retention means comprising a groove in said surface PO1' tion of the contact terminal member, a generally forwardly facing shoulder on said surface portion of the passage, and a retention bushing composed of a tough, resilient plastic material having a generally cylindrical head portion at the front end thereof and a rearwardly and radially outwardly flaring generally annular inclined skirt portion extending from said head portion to the rear end thereof and terminating in a generally annular face, said head portion having an internal flange which is seated within said groove so as to restrain the bushing against relative axial movement, and said skirt portion having its face in generally annular abutting relationship with said shoulder and engaged against said surface portion of the passage when the contact terminal member is in its fully inserted position in the insulation body, said skirt portion having a wall thickness less than the radial dimension between the contiguous surface of the contact terminal member and the radially adjacent wall of the passage and said bushing having a resilient, radially compressed substantially 360 interference fit between said surface portions and completely encompassing said contact terminal member in said fully inserted position providing a moisture seal between the contact terminal memher and the insulation body.

10. An electrical connector unit as defined in claim 9 wherein said skirt portion of the bushing inclines at an angle of greater than 15 degrees relative to the axis of the bushing when the bushing is in its free, uncompressed condition.

11. An electrical connector unit as defined in claim 9 wherein said skirt portion of the bushing inclines at an angle of greater than 15 degrees and not greater than 25 degrees relative to the axis of the bushing when the bush ing is in its free, uncompressed condition.

12. An electrical connector unit as defined in claim 9 wherein said skirt portion of the bushing inclines at an angle of about 18 degrees relative to the axis of the bushing when the bushing is in its free, uncompressed condi tion.

13. An electrical connector unit as defined in claim 10 wherein said bushing is composed of a fluoroethylene plastic material.

14. An electrical connector unit as defined in claim 10 wherein said bushing is longitudinally split to permit ex pansion of the bushing for mounting thereof on the con tact terminal member with said flange seated within said groove, said bushing being closed at the longitudinal split in said radially compressed condition of the bushing.

15. An electrical connector unit as defined in claim 10 wherein said stop means includes an annular collar on the contact terminal member, I

16. An electrical connector unit comprising a tubular outer shell having front and rear ends and having a fies sage extending therethrough between said ends, an iu-' sulation body insertable into said passage from one end so as to be supported therein with a portion of the surface of the passage in overlapping relationship with a peripheral surface portion of said insulation body, stop means on said shell and body engageable to limit the insertion of said body in the passage, and snap-in retention means engageable between said shell and body for retaining and moisture sealing said body in said passage of the shell, said retention means comprising a groove in one of said surface portions, a generally axially facing shoulder on the other of said surface portions, and a re tention bushing composed of a tough, resilient plastic material having a generally cylindrical head portion at one end thereof and a generally annular inclined skirt portion: extending from said head portion to the other end there-- of and terminating in a generally annular face, said head portion having a flange thereon which is seated within said; groove so as to restrain the bushing against relative axial;

movement, and said skirt portion inclining toward said other surface portion with the face of the skirt in generally annular abutting relationship with said shoulder and engaged against said other surface portion when said body is in its fully inserted position in said shell, said skirt portion having a Wall thickness less than the radial dimension between the contiguous surface of the body and the radially adjacent wall of the passage and said bushing having a resilient, radially compressed substantially 360 interference fit between said surface portions and completely encompassing said body in said fully inserted position providing a moisture seal between said shell and body.

17. An electrical connector unit as defined in claim 16 wherein said skirt portion of the bushing inclines at an angle of greater than 15 degrees relative to the axis of the bushing when the bushing is in its free, uncompressed condition.

18. An electrical connector unit as defined in claim 16 wherein said skirt portion of the bushing inclines at an angle of greater than 15 degrees and not greater than 25 degrees relative to the axis of the bushing when the bushing is in its free, uncompressed condition.

19. An electrical connector unit as defined in claim 16 wherein said skirt portion of the bushing inclines at an angle of about 18 degrees relative to the axis of the bushing when the bushing is in its free, uncompressed condition.

20. An electrical connector unit as defined in claim 17 wherein said bushing is composed of a fluoroethylene plastic material.

21. An electrical connector unit as defined in claim 17 wherein said skirt portion of the bushing extends in a 1.4 rearward, inclined direction from said head portion of the bushing.

22. An electrical connector unit as defined in claim 21 wherein said groove is in said peripheral surface portion of the body and said shoulder is on said passage surface portion of the shell, said skirt portion of the bushing flaring rearwardly and radially outwardly from said head portion of the bushing.

23. An electrical connector unit as defined in claim 21 wherein said groove is in said passage surface portion of the shell and said shoulder is on said peripheral surface portion of the body, said skirt portion of the bushing inclining rearwardly and radially inwardly from said head portion of the bushing.

References Cited in the file of this patent UNITED STATES PATENTS 1,031,976 Weber July 9, 1912 1,753,317 Rothen Apr, 8, 1930 2,118,448 Wallace et al. May 24, 1938 2,434,832 Bruun Jan. 20, 1948 2,532,538 Burtt et al. Dec. 5, 1950 2,695,394 Watts Nov. 23, 1954 2,700,144 Flanagan Ian. 18, 1955 2,779,008 Quackenbush Jan. 22, 1957 2,948,773 Hawes Aug. 9, 1960 3,068,443 Nava et al. Dec. 11, 1962 3,077,572 Zimmerman Feb. 12, 1963 FOREIGN PATENTS 231,270 Australia Dec. 10, 1959 1,161,384 France Mar. 24, 1958 

1. AN ELECTRICAL CONNECTOR UNIT COMPRISING A SUPPORT MEMEBER HAVING FRONT AND REAR ENDS AND HAVING A PASSAGE EXTENDING THERETHROUGH BETWEEN SAID ENDS, A SUPPORTED MEMBER INSERTABLE INTO SAID PASSAGE FROM ONE END SO AS TO BE SUPPORTED THEREIN WITH A PORTION OF THE SURFACE OF THE PASSAGE IN OVERLAPPING RELATIONSHIP WITH A PERIPHERAL SURFACE PORTION OF SAID SUPPORTED MEMBER, STOP MEANS ON SAID MEMBERS ENGAGEABLE TO LIMIT THE INSERTION OF SAID SUPPORTED MEMBER IN THE PASSAGE, AND SNAP-IN RETENSION MEANS ENGAGEABLE BETWEEN SAID MEMBERS FOR RETAINING AND MOISTURE SEALING SAID SUPPORTED MEMBER IN SAID PASSAGE OF THE SUPPORT MEMBER, SAID RETENSION MEANS COMPRISING A GROOVE IN ONE OF SAID SURFACE PORTIONS, A GENERALLY AXIALLY FACING SHOULDER ON THE OTHER OF SAID SURFACE PORTIONS, AND A RETENTION BUSHING COMPOSED OF A TOUGH, RESILIENT PLASTIC MATERIAL HAVING A GENERALLY CYLINDRICAL HEAD PORTION AT ONE END THEREOF AND A GENERALLY ANNULAR INCLINED SKIRT PORTION EXTENDING FROM SAID HEAD PORTION TO THE OTHER END THEREOF AND TERMINATING IN A GENERALLY ANNULAR FACE, SAID HEAD PORTION HAVING A FLANGE THEREON WHICH IS SEATED WITHIN SAID GROOVE SO AS TO RESTRAIN THE BUSHING AGAINST RELATIVE AXIAL MOVEMENT, AND SAID SKIRT PORTION INCLINING TOWARD SAID OTHER SURFACE PORTION WITH THE FACE OF THE SKIRT IN GENERALLY ANNULAR ABUTTING RELATIONSHIP WITH SAID SHOULDER AND ENGAGED AGAINST SAID OTHER SURFACE PORTION WHEN SAID SUPPORTED MEMBER, SAID SKIRT FULLY INSERTED POSITION IN SAID SUPPORT MEMBER, SAID SKIRT PORTION HAVING A WALL THICKNESS LESS THAN THE RADIAL DIMENSION BETWEEN THE CONTIGUOUS SURFACE OF THE SUPPORTED MEMBER AND THE RADIALLY ADJACENT WALL OF THE PASSAGE AND SAID BUSHHING HAVING A RESILIENT, RADIALLY COMPRESSED SUBSTANTIALLY 360* INTERFERENCE FIT BETWEEN SAID SURFACE PORTIONS AND COMPLETELY ENCOMPASSING SAID SUPPORTED MEMBER IN SAID FULLY INSERTED POSITION PROVIDING A MOISTURE SEAL BETWEEN SAID MEMBERS. 